Wylie told House Judiciary Democrats and the House Committee on Oversight and Government Reform during a private briefing that Bannon directed the British research firm to explore methods for "discouraging particular types of voters who are more prone to voting for Democratic or liberal candidates."

The whistleblower also told House Democrats that Bannon directed the firm to test messaging regarding Russia, Vladimir Putin and Russian expansion in Eastern Europe.

"It was the only foreign issue or foreign leader, I should say, being tested at the time I was there," Wylie told lawmakers.

Bannon was a founder of Cambridge Analytica and held a position on its board before joining the Trump campaign.

Wylie also shed light on Michael Flynn's advisory role at the research firm, saying that his function was to "open doors and look at potential contracts," for the company as a consultant.

The research firm, which Wylie described on Tuesday as a "full-service propaganda machine" has been embroiled in controversy since Facebook disclosed that it would cut ties with Cambridge Analytica over its improperly harvesting the data of 87 million Facebook users.

While Facebook has dealt with scrutiny in the matter, it has tried to shift at least some of the blame to Cambridge Analytica, characterizing it as a rogue actor that violated its data policies.

Members of the House Intelligence Committee held a separate closed-door meeting with Wylie on Wednesday.

The committee's top Democrat, Rep. Adam Schiff (D-Calif.) said in a statement after the meeting that Wylie outlined connections between Cambridge Analytica, WikiLeaks founder Julian Assange and Wikileaks, but did not provide specifics on those ties.

According to Schiff, Wylie provided new details on "Cambridge Analytica's previous experience using hacked or misappropriated data in the Nigeria campaign."

Wylie reportedly told the committee new information about the firm's outreach to Russia's Lukoil and the oil company's "relationship with Russian intelligence, its interest in Cambridge Analytica's ability to target U.S. voters through the firm's datasets."